Tuesday, February 26, 2013

In response to a couple of questions, here are some notes on how we built the wheelchair bike a few years back. Bon chance to everybody trying their hand at creative solutions for family and friends.

Goals

Make wheelchair trips using the power of a bicycle drivetrain.

Keep our heads close enough together to talk.

Use the existing wheelchair we had.

Retain the ability to fold the wheelchair for car-based trips.

Attach/Detach fairly quickly.

Early Concept

The overall design was modelled off old rickshaws. The tadpole design (with the two wheels in front) means that the cyclist's head come forwards towards the seated person's head and conversation is feasible. This contrasts strongly with the alternative where the wheelchair is towed behind and the occupant feels very distant.

As you can see, my first thought was to retain the bicycle handlebars and clip the bike forks onto some sort of axle placed between the wheels of the chair. The axle had to be unreasonably high, however, and I wasn't sure how to build a simple and strong attachment for the forks. Once I decided to modify the bike parts, I moved towards having the steering pivot in line with the wheel hubs.

You can also see that using blocks I was able to set up the tilt angle of the wheelchair to find the balance between feeling upright and raising the front wheels enough to avoid bumps and to get up driveways.

Planning the Back Half

The easiest way to draw up a plan was to cut up the donor bike, lay the parts out, and trace everything out life sized. Then I drew in straight lines to connect the parts, to represent new tubing.

Note that I turned the steering tube upside down as the angles of the tubes coming from it matched the design better that way. This required swapping over the bearing races from top and bottom, which would have been hard without access to my uncle's hydraulic press to reseat them. This could probably have been avoided.

It is essential to try and position yourself amongst the parts. This photo reveals one of the big problems in the finished product - the wheelchair handles are too near my knees. The layout pictured wasn't the final plan, but sadly I failed to adjust sufficiently.

Welding

With much help from a welding nightclass, I was able to put the frame together. My tutor did the bending in the lower left of the photo, which was a bit complex for me.

I didn't have a proper jig for setting up the welds, and didn't get the top tube on the the same plane as the seat tube, resulting in a small list to the left. The result is tolerable, however.

Attachment to the Wheelchair

My uncle, an engineer, made this actually work for me. I brought him the rough idea and he did the important machining and welding. There are more moving parts and adjustability than I would or could have made myself.

A baseplate clamped to the frame on each sideWe started by making a surface on each side to which we could attach the crosspieces. The plates are just squares of mild steel, a couple mm thick. We didn't want to weaken the wheelchair by welding it, so everything can be detached. We made clamps to attach each plate at two points on the lower horizontal rail, and the wheel axle had enough extra thread for a third point of attachment.

Steering tubeAs mentioned above, our tube was turned upside down so we swapped the bearing races. We cut down the existing forks and used them to connect upper and lower cross pieces. The lower cross-piece was welded directly to the fork, but since the top of the fork was just a threaded tube we manufactured a new 'nut' to thread on the top. My uncle made it a double ring, with the threaded nut to secure the fork/bearings and an outer ring which could rotate until the set-screws are tightened. This allowed rotational adjustment of the upper cross-piece, reducing by one the number of things we had to get just right when we welded those last parts.

Cross piecesThe lower cross-piece was just a square-section tube with steel across each end into which we drilled and threaded a hole for the hardened bolts I bought at the local auto shop. We drilled matching (but unthreaded so slightly wider) holes into a couple short lengths of steel which we attached to each end and then tack-welded to the plates after positioning the steering tube and ensuring it was central and vertical.For the upper cross pieces we made the end pieces first and bolted them to the plates. Then we fitted the cross-pieces on each side and tack-welded them at the sides and centre. Apparently there was some risk of deformation with all the final welding, so we did it in short spurts and things still fit reasonably well.

Brakes

You don't want a bike, particularly not a heavy one, without brakes. The wheelchair only had lock-on brakes, which weren't good enough. I would have liked disc brakes, but couldn't see how to do that. What I did have was lots of old caliper brakes from 10-speeds, which I found fitted okay once I increased the spacing between the wheel and the (black) push-rim.

The first photo shows them attached to a cross-bar which runs right across the chair, but since this prevented folding I welded on a vertical piece and gained a second attachment point. Rough, but ready.

To pull the breaks I put some old mtb levers on the wheelchair handles. These are great when walking the chair down slopes, too - much nicer to squeeze the hands than lean back against the momentum of the chair.

Final Results

A few last pictures for you. Since all the special bits were detachable from the wheelchair it was easy to take them off and paint them a cheery yellow. The leftover paint served for the altered sections of the rear frame and the connectors.

I find that it takes a couple of minutes to bolt or unbolt - slightly longer when I'm out of practise. I added SPD pedals, because you want any extra power you can get on hills. As mentioned, the posture is a bit bent over and there is that slight list to the left, but for a first crack we've been very happy.

Another thing to mention is a seatbelt. We got a simple lap belt for Heather to use so she doesn't fall out if we hit a bump. It is scary enough facing traffic from that open front seat, so the psychological benefit is also important.

Gears

One thing I haven't mentioned is gearing. I have cables and levers for both the front and rear gears, but have never found a good way to mount them. In practise, I crash between top and bottom on the rear cluster, and never change from the smallest front ring. Not sure what I'll do about that.

That's all for now. Hope it inspires you and helps with some practical details.

Saturday, September 15, 2012

What a day for a bike ride! The rain held off until we'd packed up, but the wind was strong from the get-go and disrupted both the riders and the supporters. I only rode 40k, but considerably faster than I would normally ride into such a wind. (Actually, I would change my schedule if possible.) By the time I got home and had a long bath my body feels fine, but I have no oomph and my legs feel particularly empty. Curiously, my most troubled body parts are my eyes and sockets - they feel very dry and windblasted.

The picture below shows the start/finish area, and should feature a line of gazebos on the far side where the supporters are clustered. They were already up when we arrived at 7; we were fixing one at 7:30, and and 9 they were taken down after two had been written off.

Today was the Poverty Cycle, a charity ride that my work is trying to establish. Last year we trialled a family-fun-day model, but this year went with a corporate challenge format. Teams of 5, racing nine rider-laps of a 20km course with no more than two riders going at any one time. Most of the course was flat, but there was a big hill about 3/4 of the way round.

My team did not win. By the time we finished our 8th lap (4 pairs), prize-giving had already started and our final rider couldn't see the point. Everybody had at least one lap, though.

The winning team was a bit more committed: by 7:15am (for an 8:30 start) they were on the trainers in a stall beside the parking area and out of the wind. They smoked everybody, averaging 35 minutes/lap.

I rode in the 2nd and 4th pairs. First up I paired with Richard, Doesn't he look like the boss and me the working man in my coarse woollen suit? I picked the suit up from the Sallies in Te Aroha, two weeks ago, for just $15. Couldn't resist, and I expected that Richard would be in street clothes since he is already riding around to appointments dressed like that.

One good thing about the weather - it helped keep us cool. I changed to my everyday road helmet for my second time round, which had much better airflow (but is boring black).

Richard was running aero bars, and kindly pulled me around the track. He is a much stronger rider than me, probably due to commuting up a nasty hill every morning, so even leading into the wind his pace was all I could handle. The one time I took over, in a sheltered spot, I misjudged and sapped my energy just before the big hill climb. I actually felt better and better going up the hill, as my system caught up on itself.

The most exciting part of the ride came right at the end of the first lap. We turned into the start/finish area, and two of those sign holders (behind us in the photo above) blew across our path! Thankfully far enough ahead to avoid quite easily, but it did start the heart pounding.

Second time round was a bit hard at first, after eating a couple croissants and standing in the wind for ages, but the flat sections were actually easier overall. Franck (pictured below with the person I entrusted my camera to) set a pace better matched to mine, then dropped me on the hill where I didn't have much left in my tank. I shamelessly drafted most of the way again, as he never tucked in behind when I was leading - why do that work for somebody who doesn't appreciate it?

I'm pretty knackered tonight, but it has been a good day. I can't see myself taking up racing, but I might give it a go again next year. My friends chipped in $520 for anti-trafficking work in Nepal, so I'm pretty pleased about that. Thanks to everybody who sponsored me.

Friday, August 5, 2011

Was tickled to show the Yuba off to David Haywood and whanau on they way out of the Orcon Great Blend last night. Apparently they've considered a cargo bike with two child seats. Hope I restrained my enthusiasm below the boring fanatic threshold.

Then cycled through the Wynyard Quarter due to open tomorrow. Nice spaces, and a handy ramp up to the viewing platform. That nice existing frontage around half the Viaduct Basin will hopefully connect right around (timeline suggests 2013?) and should benefit from having more outdoor punters in the area rather than the restaurant/bar clientele of the Viaduct. Speaking of which, the bridge provides nice pedestrian access between Wynyard and the Viaduct which could change the dynamic of the whole area.

Got several comments appreciating the bike lights as I cruised around, but uncertain how much to value the opinion of the guys peeing off the wharf.

Monday, April 11, 2011

Our pollution figures for this year have increased a long way back towards their 2007 levels. Major contributors were my trip to Christchurch for a polo tournament and the purchase of a new laptop.Looking ahead, we have decided to set a target of reaching the current1 globally sustainable per capita emissions level (~1.2T CO2e) by 2050. This requires us to reduce by just over 3% each year, compounding. That will become increasingly challenging, and require systemic change2 around us as well as personal lifestyle choices.

For the new year, we plan to find 2% by halving our regular butter and sugar consumption. These are mostly used for baking, for which we will increasingly use margarine. We are testing various recipes with less sugar, and may alter our selection of baked treats. As a side benefit, this could be healthier.3

We want to make the remaining 1% savings amongst our "irregular" consumption: rarely taken actions or supplies for special occassions. These are the source of all variation recorded between this year and last, as we haven't performed a new baseline audit and continue to use our 2010 figures. The very irregularity of this consumption makes it harder to work with. Over time we will expect continuing fluctuation, but require an underlying downward trend.

Accurately reporting this will require an improvement in our accounting practise. A likely first step will be to amortise the big figures, a practise we have so far applied only to the house. Our new laptop will be used over several years, but we thought there would be enough similar items from year to year to smooth out. That will be less and less the case as we make smarter purchases.4 We may also plan to fly domestically once every n years, rather than on a most-years basis, and budget that into our regular baseline.

__________1) With world population expected to rise to perhaps 9 billion by 2050, the per capita sustainable emissions level will presumably decrease.2) 20% of our current emissions are due to public services we have no direct choice about consuming. Yesterday Heather initiated conversation with a Dunedin city councillor on this very topic, building on a hint of shared interest.3) Going significantly dairy free would make a much bigger impact on the carbon numbers, as well as distance us from an industry which has recently expanded beyond the country's carrying capacity. We remain held back by uncertainty over how to supply Heather's calcium needs and reluctance to overhaul the complex dietary system we have developed for her over eight years of illness.4) The laptop also stands out because we bought it new, rather than second hand. We have chosen to assign all emissions responsibility to the initial (retail) purchaser, so the choice between new and second-hand is much more stark in carbon terms than dollar terms. We could change this policy, at least on large items, which would be more accurate in many ways but opens the thorny question of how to apply depreciation.

Monday, February 21, 2011

Yesterday we went to the beach to try out something new - the Vera Wansbrough Memorial Beach Wheelchair. The chair has fat, low pressure wheels to glide over the grass and sand right into the water. The goal was to get Heather to the water more often, which seemed a fitting use for some money inherited from her beach-loving grandmother.

The chair was a great success, and will be well worth the money (approx $600) if we get out a few more times each summer. No more parking the normal chair where the path ends and carrying Heather across the sand into the water. No more carrying her back up, all slippery and wet.

In the future we won't take the other wheelchair, but took it just in case yesterday. It did provide a nice place to sit and talk to Heather, while she reclined in her personal lounger.

The wheels also make a handy seat.

With its big wheels, the whole contraption floats when nobody is sitting in it. With a person sitting in it, the wheels still float but the foot end gradually sinks. We hope that a simple floatation device strapped on that end will give us a fully floating option that Heather can swim on and off.

The following video shows how smooth the process of coming out of the water was. If you're wondering why we pause, back up, and move forward again, that's me discovering where the floating wheels touch bottom and start turning. I also stop to check if it works to push from the head end, but decide that it works best to pull from the feet. We do need a handle to save stooping over and avoid lifting too high and banging poor Heather's head.

MUTE BEFORE WATCHING - NASTY STATIC

Do try this at home. Our system is cobbled together from a pair of 49cm Wheeleez Wheels (distributed in NZ by BeachWheels.co.nz) and a $50 fold-out beach lounger we were given several years ago. We bought an axle and locking pins with the wheels, and ran the axle through a piece of hdpe pipe I had around the house (it was too small for making polo mallets). Two hose clamps were also required. Here are all the parts:

The pipe is simply lashed to the mid-section of the lounger, using hemp string. I had to use a needle to thread the string through the plastic canvas, to get the axle at a suitable balance point.

Using the pre-fab lounger saved heaps of effort putting the canvas onto a frame, but it was never designed to go into salt water and will presumably be replaced in time. By then it will have earned an honourable place in history for proving out the idea.

The frame was designed to have a support under the knee, which doesn't work when it is being lifted and the force goes the other way. To stop the lounger folding up at that point I put the hose clamps on to hold the two tubes together. The clamps loosen with a screwdriver and slide off the end of the the lower tube, allowing the lounger to fold again for transport. So far it is working, but you can see that the previous (pivoting) attachment between those tubes has been strained during testing. I think that the strain has eased since I moved the axle, but only time will tell.

Thursday, October 21, 2010

So it's been almost 3 months, but here's my report for the record from the polo comp in Christchurch.

Winter Whack - 3rd Place Winners!

Our team started out with a good couple of wins, but couldn't sustain the intensity and got wasted by in 3 minutes flat by the eventual champs - Polo Disco. In the 2nd/3rd playoff we put up stiffer resistance, but eventually the same team which twice beat our fellow Aucklanders put paid to us as well. Props to Glenn who sorted out the Auckland teams - he must of done a good job of balancing us up as we came out 3rd and 4th at the end of the day.

Play was pretty intense at times - you had to commit the body right up to the action, which resulted in a bunch of spills. At one point I lost my rear brake in our first game, and eventually traded the bike off for Glenn's. Playing so many games at that intensity did take it's toll, and I reckon that was a factor in the later games. Polo Disco was clearly a cut above us in skill as well. Not just us, as they swept up the entire field pretty handily. I think they had 3 goals scored against them all day, but thankfully nobody enforced the down-trou rule or there'd have been a lot of flesh on display.

The whole tournament had a great atmosphere, and everybody seemed to have fun. There was quite a range of skill levels, with people drawn in to make up teams or whole teams of occasional players. No way could Auckland have fielded 21 players like Christchurch did, but hopefully a return tourney will pull out a few of our potential/interested people.

Everybody's first question on arrival was why there were so many vegans in the Auckland delegation. The Chch crew is based around fathers who can't get out for mountain-biking like they used to, whereas I can't think of any player from Akl who has kids. Very different demographics didn't hinder us enjoying a night at the pub together beforehand and an aftermatch dinner at the Dux (which has several vegan options).

One last thing to point out - the club house next to the courts is a great idea. It allows them to store edging for the court, rather than losing the ball under the raggedy fence edge or digging it out of weedy gutters. We need something like that in Akl.

Cycle Friendly City

Christchurch was truly fabulous to cycle in. Lots of cycle lanes. Nary a hill through much of the city. A beautiful park with good tracks to ride through. Most importantly - lots of other cyclists to keep the drivers in the habit of looking and waiting.

They also allow bikes on buses, and I went 30kms out to Rangiora for $5.80 each way to visit a colleague. Get off at the other end with your bike, cycle to a store to pick up a drink and choccies, and find your mate's house. So much harder on foot. But do allow for the fact that the first bus after school gets out may have a full rack.

So thanks, Christchurch! Thanks to Craig for being the main man behind the tournament, and thanks to Mads and Malcs for putting me up and feeding me lots of warm, scrummy soup. (I did get sunburnt on the big day, but it wasn't always warm down there.)

About Me

Here you will mostly read about my love for bicycles and how much fun they are to ride. I have a commuting bike, another for shopping, plus one for bike polo. And maybe one or two others, since you ask.